U.S. patent number 6,066,218 [Application Number 09/065,295] was granted by the patent office on 2000-05-23 for method and apparatus for assembling an optical recording medium.
This patent grant is currently assigned to 3M Innovative Properties Company. Invention is credited to Kevin J. Bangen, Richard E. Bennett, Gary K. Kuhn, Jack L. Perecman, Gary L. Romberg.
United States Patent |
6,066,218 |
Kuhn , et al. |
May 23, 2000 |
**Please see images for:
( Certificate of Correction ) ** |
Method and apparatus for assembling an optical recording medium
Abstract
Methods and apparatus for applying a bonding layer to a member
of an optical recording medium and for bonding together members of
an optical recording medium. The methods and apparatus are useful
for assembling optical recording media such as compact disks (CDs)
and digital versatile disks (DVDs), and are particularly well
suited for use with pressure sensitive adhesives. A preferred
method of assembling together first and second members of an
optical recording medium, wherein each of the members includes an
inner surface and an outer surface, wherein at least one of the
inner surfaces includes a bonding layer thereon, and wherein at
least one of the members includes a data storage surface, includes
the steps of: a) curving the first member such that the first
member inner surface is convex, wherein the first member inner
surface includes an outer annulus, and wherein the outer annulus
includes a first portion and a second portion; b) orienting the
second member such that the second member inner surface faces the
first member inner surface, wherein the second member inner surface
includes an outer annulus, and wherein the outer annulus includes a
first portion and a second portion; c) contacting the first portion
of the first member outer annulus and the first portion of the
second member outer annulus together under pressure; and d)
rotating the first and second members relative to one another so as
to progressively contact under pressure the first member inner
surface and second member inner surface together from their
respective outer annulus first portions to their respective outer
annulus second portions to thereby attach together the inner
surfaces of the first and second members. A similar method for
applying the bonding layer to one member is disclosed. Also
disclosed are apparatus for use with the above methods.
Inventors: |
Kuhn; Gary K. (Stillwater,
MN), Perecman; Jack L. (Golden Valley, MN), Romberg; Gary
L. (River Falls, WI), Bangen; Kevin J. (Scandia, MN),
Bennett; Richard E. (Hudson, WI) |
Assignee: |
3M Innovative Properties
Company (St. Paul, MN)
|
Family
ID: |
22061709 |
Appl.
No.: |
09/065,295 |
Filed: |
April 23, 1998 |
Current U.S.
Class: |
156/87;
G9B/7.194; G9B/7.139; 156/160; 156/582 |
Current CPC
Class: |
B29C
65/48 (20130101); B29C 66/83513 (20130101); B30B
15/061 (20130101); G11B 7/26 (20130101); B32B
37/0007 (20130101); B29C 66/1122 (20130101); B29C
66/8242 (20130101); G11B 7/24 (20130101); B29C
65/7885 (20130101); B29C 66/342 (20130101); B32B
38/1866 (20130101); B29C 66/345 (20130101); B29C
66/452 (20130101); B29C 65/7847 (20130101); B32B
37/10 (20130101); B29C 65/4825 (20130101); B29L
2017/005 (20130101); B29C 65/483 (20130101); B29C
65/485 (20130101); B29C 65/4815 (20130101); B32B
2429/02 (20130101); B29C 65/4835 (20130101); B29C
66/71 (20130101); B29C 66/727 (20130101); B29C
65/4845 (20130101); B29C 65/4865 (20130101); B29C
66/71 (20130101); B29K 2023/00 (20130101); B29C
66/71 (20130101); B29K 2023/38 (20130101); B29C
66/71 (20130101); B29K 2033/08 (20130101); B29C
66/71 (20130101); B29K 2033/12 (20130101); B29C
66/71 (20130101); B29K 2063/00 (20130101); B29C
66/71 (20130101); B29K 2069/00 (20130101) |
Current International
Class: |
B29C
65/00 (20060101); B29C 65/48 (20060101); B29C
65/78 (20060101); G11B 7/26 (20060101); G11B
7/24 (20060101); B32B 031/10 () |
Field of
Search: |
;156/295,87,558,582,285,160 |
Foreign Patent Documents
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0 326 358 |
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Aug 1989 |
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EP |
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0 405 582 A2 |
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Jun 1990 |
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EP |
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0 509 472 A2 |
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Apr 1992 |
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EP |
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2 693 149 |
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Jan 1974 |
|
FR |
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2 606 198 |
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May 1988 |
|
FR |
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Other References
Patent Abstracts of Japan, vol. 017, No. 550 (P-1624), Oct. 4, 1993
& JP 05 151625 A (TDK Corp), Jun. 18, 1993. .
Patent Abstracts of Japan, vol. 013, No. 087 (P0835), Feb. 28, 1989
& JP 63 269301 A (Kanegafuchi Chem Ind CO Ltd), Nov. 7, 1988.
.
Patent Abstracts of Japan, vol. 015, No. 296 (P-1231), Jul. 26,
1992 & JP 03 102660 A (Fuji Photo Film Co Ltd), Apr. 30, 1991
& JP 03 102660 A (Fuji Photo Film Co) Apr. 30, 1991..
|
Primary Examiner: Ball; Michael W.
Assistant Examiner: Piazza; Gladys
Attorney, Agent or Firm: Trussell; James J.
Claims
What is claimed is:
1. A method of assembling together first and second members of an
optical recording medium, wherein each of the members includes an
inner surface and an outer surface, wherein at least one of the
inner surfaces includes a bonding layer thereon, and wherein at
least one of the members includes a data storage surface, the
method comprising the steps of:
a) curving the first member such that the first member inner
surface is convex, wherein the first member inner surface includes
an outer annulus, and wherein the outer annulus includes a first
portion and a second portion;
b) curving the second member such that the second member inner
surface is convex and orienting the second member such that the
second member inner surface faces the first member inner surface,
wherein the second member inner surface includes an outer annulus,
and wherein the outer annulus includes a first portion and a second
portion;
c) contacting the first portion of the first member outer annulus
and the first portion of the second member outer annulus together
under pressure; and
d) rotating the first and second members relative to one another so
as to progressively contact under pressure the first member inner
surface and second member inner surface together from their
respective outer annulus first portions to their respective outer
annulus second portions to thereby attach together the inner
surfaces of the first and second members.
2. The method of claim 1, wherein steps a) and b) comprise curving
the first and second members to substantially the same contour.
3. The method of claim 1, wherein step a) comprises curving the
first member to an arcuate contour.
4. The method of claim 3, wherein step b) comprises curving the
second member members to an arcuate contour.
5. The method of claim 1, wherein step d) further includes
maintaining the entire inner surface of one of said first and
second members curved.
6. The method of claim 5, comprising the further step of:
e) concurrently with step d), progressively releasing the curvature
of the other one of said first and second members as the members
attach together.
7. The method of claim 1, comprising the further step of:
e) concurrently with step d), progressively releasing the curvature
of both of said members from the respective first portions of the
annulus to the respective second portions of the annulus as the
members attach together.
8. The method of claim 1, wherein step d) further includes
translating the first member about a first arcuate path and
translating the second member about a second arcuate path.
9. The method of claim 1, wherein the bonding layer comprises a
pressure sensitive adhesive.
10. The method of claim 1, wherein step a) includes releasably
mounting the first member on a first fixture having a convex
surface.
11. The method of claim 10, wherein step a) includes releasably
mounting the first member on a convex surface of a resilient pad on
the fixture.
12. The method of claim 11 wherein the resilient pad is a foam
pad.
13. The method of claim 10, wherein the first member is held to the
convex surface of the fixture by a vacuum.
14. The method of claim 1, wherein step a) includes releasably
mounting the first member on a first fixture having a convex
surface, and wherein step b) includes releasably mounting the
second member on a second fixture having a convex surface.
15. A method of applying a bonding layer to a member of an optical
recording medium, the bonding layer including an exposed surface,
the member including an inner surface and an outer surface, the
method comprising the steps of:
a) curving the member such that the member inner surface is convex,
wherein the member inner surface includes an outer annulus, and
wherein the outer annulus includes a first portion and a second
portion;
b) curving the bonding layer such that the exposed surface is
convex and orienting the bonding layer such that the exposed
surface of the bonding layer is facing the member inner
surface,
c) contacting the first portion of the member outer annulus and
exposed surface of the bonding layer together under pressure;
and
d) progressively contacting the exposed surface of the bonding
layer from the first portion of the member outer annulus to the
second portion of the member outer annulus to thereby bond together
the member inner surface and the bonding layer.
16. The method of claim 15, wherein steps a) and b) comprise
curving the member and the bonding layer to substantially the same
contour.
17. The method of claim 15, wherein step a) comprises curving the
member to an arcuate contour.
18. The method of claim 17, wherein step b) comprises curving the
bonding layer to an arcuate contour.
19. The method of claim 15, wherein step d) further includes
maintaining the entire inner surface of the member curved.
20. The method of claim 15, wherein step d) further includes
translating the member about a first arcuate path and translating
the bonding layer about a second arcuate path.
21. The method of claim 15, wherein the bonding layer comprises a
pressure sensitive adhesive.
22. The method of claim 15, wherein the optical recording medium
member is a first member, and comprising the further step of:
f) thereafter bonding a second member of the optical recording
medium to the first, wherein the second member includes an inner
surface facing the inner surface of the first member.
23. The method of claim 22, wherein the inner surface of the second
member includes an outer annulus, wherein the outer annulus
includes a first portion and a second portion, and wherein step f)
comprises:
f. i) curving one of the first and second members such that its
inner surface is convex;
f. ii) orienting the other of the first and second members such
that the first and second inner surfaces are facing one
another;
f. iii) contacting the first portion of the first member outer
annulus and the first portion of the second member outer annulus
together under pressure; and
f. iv) rotating the first and second members relative to one
another so as to progressively contact under pressure the first
member inner surface and second member inner surface together from
their respective outer annulus first portions to their respective
outer annulus second portions to thereby attach together the inner
surfaces of the first and second members.
24. The method of claim 23, wherein step f. ii) further includes
curving the other of the first and second members such that its
inner surface is convex.
25. The method of claim 24, wherein steps f. i) and f. ii) comprise
curving the first and second members to substantially the same
contour.
26. The method of claim 23, wherein step f. i) comprises curving
the member to an arcuate contour.
27. The method of claim 24, wherein steps f. i) and f. ii) comprise
curving the first and second members to an arcuate contour.
28. The method of claim 24, wherein step f. iv) further includes
translating the first member about a first arcuate path and
translating the second member about a second arcuate path.
29. The method of claim 15, wherein step a) includes releasably
mounting the member on a first fixture having a convex surface.
30. The method of claim 29, wherein step a) includes releasably
mounting the first member on a convex surface of a resilient pad on
the fixture.
31. The method of claim 30, wherein the resilient pad is a foam
pad.
32. The method of claim 29, wherein the member is held to the
convex surface of the fixture by a vacuum.
33. The method of claim 15, wherein step a) includes releasably
mounting the member on a first fixture having a convex surface, and
wherein step b) includes releasably mounting the bonding layer on a
second fixture having a convex surface.
34. The method of claim 24, wherein step f. i) includes releasably
mounting the member on a first fixture having a convex surface.
35. The method of claim 34, wherein the member is held to the
convex surface of the fixture by a vacuum.
36. The method of claim 25, wherein step f. i) includes releasably
mounting the one member on a first fixture having a convex surface,
and wherein step f. ii) includes releasably mounting the other
member on a second fixture having a convex surface.
Description
TECHNICAL FIELD
The present invention relates to methods and apparatus for applying
a bonding layer to one member of an optical recording medium such
as a compact disk or a digital versatile disk, and to methods and
apparatus for assembling members of an optical recording medium
together.
BACKGROUND OF THE INVENTION
Optical recording media such as compact disks (CDs) have become
very popular as a means for storing and/or reproducing information
such as audio information, video information or other data. CDs
with one information surface usually include, for example, a spiral
or segmented information track composed of convex and concave
portions (pits) formed on the surface of a disk-shaped resin
substrate comprising, for example, polymethylmethacrylates and
polycarbonates. A reflection film of, for example, aluminum (Al) is
deposited on the information bearing surface of the substrate and a
protection film is formed thereon.
The storage capacity of such a CD is too small to store, for
example, moving-picture information such as a movie for a
sufficiently long recording or play time. In order to increase the
storage capacity, storage media having two disks which are adhered
together, such as, for example, magneto-optical disks (MO) have
been suggested.
Recently, a high storage capacity format for digital video storage
has been suggested as DVD (digital versatile disk, sometimes also
digital video disk). DVDs can be divided into DVD-ROMs which are
exclusively for reproduction, and DVD-RAMs which can also be used
for data storage, DVD-Rs which are recordable once ("write once,
read many"), DVD-Audios and DVD-Videos. The format for DVD-ROMs,
for example, has been provisionally defined by an industry (ECMA,
Executive Committee of the DVD Consortium) as ECMA/TC 31/97/2,
Geneva, Switzerland, January 1997, and presently comprises 4.7
gigabytes (GB), 8.5 GB, 9.4 GB and 17 GB formats. The different
formats are described in some detail on p. 5 of ECMA/TC 31/9712 as
types A-D and in EP 0,725,396 (see, in particular, FIG. IC-IF).
DVDs generally comprise two disk shaped members, the inner surfaces
of which are bonded together with a bonding layer which must be
light transmissive if the information on one or more of the
recording layers is read through the bonding layer. In the 4.7 GB
single layer format only one of the members comprises an
information storing layer formed by the inner surface of the
substrate which exhibits a sequence of pits with a minimum size of,
for example, 0.4 .mu.m. An Al layer is deposited on the information
storing layer optionally followed by a protective coat. The inner
surface of the second substrate which is a dummy substrate is
bonded to the inner surface of the first member, i.e., for example,
to the Al layer or to the protective coat layer. The 8.5 GB and, in
particular, the 9.4 GB and 17 GB formats exhibit more complicated
constructions and usually comprise an information storing layer on
each substrate. For the 8.5 GB format a single side/dual layer
construction is described on p. 3, FIG. 3 of the Bulletin: 101
December 1996 provided by Imation Corporation of Oakdale, Minn.,
available on the Internet under the address
http://www.imation.com/dsp/optical/dvd/techbull.html.
Bonding of the two members of DVDs or other high storage capacity
optical recording media is a particular problem because of the
demanding technical requirements. In Tape-Disk Business, 10 (1996),
no. 9, p.13, three bonding technologies are described using
hot-melt adhesives, radically ultraviolet (UV) curable or
cationically UV curable liquid adhesives, respectively. Hot-melt
adhesives can be attached to the inner surface of the members, for
example, by roll-coating whereas radically or cationically UV
curable liquid adhesives can be applied with, for example,
spin-coating or screen-printing techniques.
While UV-curable liquid adhesives may result in bondings having a
low defect density or in a virtually "perfect bubble-free system"
as is claimed in the Tape-Disk Business article, their use also has
some disadvantages such as, for example, corrosion problems of the
members and, in particular, of the reflective films used herein,
the incompatibility of liquid adhesives with mass production
requirements and handling problems as is pointed out in the
background section of EP 0,330,197. Additionally, UV curing is
usually difficult because of the high UV-absorbance of the
substrates. This necessitates high UV intensities and/or long times
for curing resulting in unacceptably high tilt or warpage.
UV-curing at the edges of the members where oxygen is present, is
difficult. EP 0,330,197 suggests the use of a smooth-surfaced
silicone-based double-side pressure-sensitive adhesive film which
is applied to the inner surface of the first disk, followed by
pressurizing the first disk with the attached adhesive film between
rollers, removing the release liner, attaching the second disk to
the exposed pressure-sensitive adhesive film, and application of
uniform pressure. A similar process is described in M. Nakamura et
al., Two-sided tape used to glue DVDs together, Japanese Journal of
Electronic Materials (Denshi Zairoy), special edition June 1996,
pp. 46-49. In a first step the first member is secured with the
first reflective layer being exposed, and the adhesive sheet is
then adhered to the first substrate using a rubber roller. Then the
release liner is removed from the adhesive layer, the inner surface
of the second member is attached to the adhesive sheet and the
assembly is then press-bonded in a pressure boiler to expel the
bubbles which have been formed during the lamination step.
Expelling the bubbles requires that the second substrate is pushed
down towards the exposed adhesive layer adhered to the inner
surface of the first substrate using, for example, a pressure
cylinder exerting high pressure. This often results, however, in
the formation of large bubbles and/or an irreversible deformation
of the adhesive layer near the bubble. Another problem is that the
pressure sensitive adhesive layer is squeezed out between the edges
of the members. The surface of the members typically is not
essentially flat but may comprise protrusions or indentations.
Disk-shaped members with a centered hole, for example, typically
exhibit a rim around said centered hole to allow for stacking the
optical recording medium on a vertically extending pin. When
quickly pushing down the second member by means of a piston, for
example, any mismatch in the orientation between the piston and the
second member may result in introducing high tilt or warpage and/or
scratches on the surface of the member. When using a piston it is
furthermore difficult to bond the members together without creating
unacceptable high values of
tilt and/or warpage in the DVD. Pushing down the second member onto
the exposed adhesive layer and expelling the air is required in the
method described in the above article from the Japanese Journal of
Electronic Materials to obtain cycle times of no more than 10
seconds per DVD.
The use of a double-sided adhesive layer in DVDs is also mentioned,
for example, in JP 07-262,619, JP 07-014,215 and JP 08-096,415.
It is seen that it is desirable to provide an apparatus and method
for applying a bonding layer to a member of an optical recording
medium that minimizes or eliminates entrapped bubbles and/or that
provides a flat member. It is also desirable to provide an
apparatus and method for assembling two members of an optical
recording medium that minimizes or eliminates entrapped bubbles
and/or that provides a flat medium. Preferably, such an apparatus
and method is particularly well suited for use with pressure
sensitive adhesives, although it is not limited thereto.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a method of assembling
together first and second members of an optical recording medium
Each of the members includes an inner surface and an outer surface,
at least one of the inner surfaces includes a bonding layer
thereon, and at least one of the members includes a data storage
surface. The method comprises the steps of: a) curving the first
member such that the first member inner surface is convex, wherein
the first member inner surface includes an outer annulus, and
wherein the outer annulus includes a first portion and a second
portion; b) orienting the second member such that the second member
inner surface faces the first member inner surface, wherein the
second member inner surface includes an outer annulus, and wherein
the outer annulus includes a first portion and a second portion; c)
contacting the first portion of the first member outer annulus and
the first portion of the second member outer annulus together under
pressure; and d) rotating the first and second members relative to
one another so as to progressively contact under pressure the first
member inner surface and second member inner surface together from
their respective outer annulus first portions to their respective
outer annulus second portions to thereby attach together the inner
surfaces of the first and second members.
In a preferred embodiment of the above method, step b) further
includes curving the second member such that the second member
inner surface is convex. More preferably, steps a) and b) comprise
curving the first and second members to substantially the same
contour.
In another preferred embodiment of the above method, step a)
comprises curving the first member to an arcuate contour. In
another embodiment, steps a) and b) comprise curving the first and
second members to an arcuate contour. Optionally, step d) further
includes maintaining the entire inner surface of one of said first
and second members curved.
Another preferred embodiment of the above method includes the
further step of: e) concurrently with step d), progressively
releasing the curvature of the other one of said first and second
members as the members attach together.
Another preferred embodiment of the above method includes the
further step of: e) concurrently with step d), progressively
releasing the curvature of both of said members from the respective
first portions of the annulus to the respective second portions of
the annulus as the members attach together.
Preferably, step d) of the above method further includes
translating the first member about a first arcuate path and
translating the second member about a second arcuate path.
In another preferred embodiment of the above method, step a)
includes releasably mounting the first member on a first fixture
having a convex surface. This step can further comprise releasably
mounting the first member on a convex surface of a resilient pad on
the fixture. In one embodiment, the resilient pad is a foam pad In
one preferred embodiment, the first member is held to the convex
surface of the fixture by a vacuum.
In another preferred embodiment of the above method, step a)
includes releasably mounting the first member on a first fixture
having a convex surface, and wherein step b) includes releasably
mounting the second member on a second fixture having a convex
surface.
Another aspect of the present invention provides a method of
applying a bonding layer to a member of an optical recording
medium. The bonding layer includes an exposed surface. The member
includes an inner surface and an outer surface. The method
comprises the steps of: a) curving the member such that the member
inner surface is convex, wherein the member inner surface includes
an outer annulus, and wherein the outer annulus includes a first
portion and a second portion; b) orienting the bonding layer such
that the exposed surface of the bonding layer is facing the member
inner surface; c) contacting the first portion of the member outer
annulus and exposed surface of the bonding layer together under
pressure; and d) progressively contacting the exposed surface of
the bonding layer from the first portion of the member outer
annulus to the second portion of the member outer annulus to
thereby bond together the member inner surface and the bonding
layer.
In a preferred embodiment of the above method, step b) further
includes curving the bonding layer such that the exposed surface is
convex. More preferably, steps a) and b) comprise curving the
member and the bonding layer to substantially the same contour.
In another preferred embodiment of the above method, step a)
comprises curving the member to an arcuate contour. More
preferably, steps a) and b) comprise curving the member and the
bonding layer to an arcuate contour.
In another preferred embodiment, step d) further includes
maintaining the entire inner surface of the member curved.
In another preferred embodiment of the above method, step d)
further includes translating the member about a first arcuate path
and translating the bonding layer about a second arcuate path.
The above method may further include bonding a second member to the
first member which already has a bonding layer thereon. Preferably,
this is done in accordance with any of the embodiments of the first
method described above.
Yet another aspect of the present invention provides an apparatus
for releasably supporting a first member of an optical recording
medium during assembly of the medium. The apparatus comprises: a) a
frame; b) a first rotary support mounted on the frame; and c) a
first fixture mounted on the rotary support, the fixture including
a first convexly curved surface for releasably holding the optical
recording medium member; wherein the rotary support is mounted on
the frame so as to rotate about a first axis from a first position
to a second position, and wherein the first axis does not intersect
the convexly curved surface.
In one preferred embodiment of the above apparatus, the fixture
further includes a first resilient pad, the resilient pad including
the convexly curved surface. Preferably, the resilient pad is a
foam pad.
In another preferred embodiment of the above apparatus, the fixture
further includes a first locating pin extending from the convexly
curved surface for engagement with the optical recording medium
member. Preferably, the pin is mounted on the fixture so as to be
able to move from a first position wherein the pin extends a first
distance from the convexly curved surface to a second position
wherein the pin extends a second smaller distance from the convexly
curved surface. Preferably, the pin is biased towards the first
position.
In another preferred embodiment of the above apparatus, the fixture
is attached to a vacuum source, and the convexly curved surface
includes holes therein in communication with the vacuum source.
In another preferred embodiment, the convexly curved surface of the
fixture includes a pressure sensitive adhesive thereon for
releasably securing the optical recording medium member.
In another preferred embodiment of the above apparatus, the
convexly curved surface of the fixture is arcuate. Preferably, the
arcuate surface of the fixture is at a radial distance from the
rotary support first axis, and the arcuate surface has a radius of
curvature substantially equal to the radial distance.
In another preferred embodiment of the above apparatus, the
apparatus further comprises: d) a second rotary support mounted on
the frame; and e) a second fixture mounted on the rotary support,
the second fixture including a second convexly curved surface for
releasably holding a second member of the optical recording medium
member. When the first and second rotary supports are in their
respective first positions, the first and second fixtures are not
aligned with one another, and when the first and second rotary
members are in their second respective positions, the first and
second fixtures are aligned with one another. The second rotary
support is mounted so as to rotate about a second axis from a first
position to a second position, wherein the second axis does not
intersect the second convexly curved surface.
The present invention also provides a member of an optical
recording medium having a bonding layer thereon applied by any of
the methods described herein. The present invention also provides
an optical recording medium comprising two members assembled
together by any of the methods described herein.
Certain terms are used in the description and the claims that,
while for the most part are well known, may require some
explanation. It should be understood that when referring to
elements of the optical recording medium or the assembling
apparatus as being "curved," this means that such an element bends
in a smooth, continuous fashion. When referring to a curved element
as being "arcuate," this means that such an element has the shape
of a segment of a circle. The term "data storage surface" refers to
a surface in or on one or both of the first and second members of
the optical recording medium that already contains optically
readable data or that is capable of having optically readable data
subsequently imparted thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be further explained with reference to
the appended Figures, wherein like structure is referred to by like
numerals throughout the several views, and wherein:
FIG. 1 is an exploded view showing the first and second members of
an optical recording medium according to a preferred embodiment of
the present invention;
FIG. 2 is a cross-sectional view of the optical recording medium of
FIG. 1;
FIG. 3 is an isometric view of a preferred embodiment of the
apparatus of the present invention, useful for carrying out a
preferred embodiment of the method of the present invention;
FIG. 4 is a side view of the apparatus of FIG. 3;
FIG. 5 is an exploded view of a preferred embodiment of a fixture
for use with the apparatus and method of the present invention;
FIG. 6 is an isometric view of a first fixture mounted on the
apparatus of FIG. 3;
FIG. 7 is an isometric view of an alternate preferred embodiment of
a fixture for use with the apparatus and method of the present
invention;
FIG. 8 is an isometric view of a second fixture mounted on the
apparatus of FIG. 3;
FIGS. 9a, 9b, and 9c are side views of a portion of a preferred
apparatus of the present invention carrying out a preferred
embodiment of a method according to the present invention;
FIGS. 10a, 10b, and 10c are front elevational views of a portion of
a preferred apparatus of the present invention carrying out a
preferred embodiment of another method according to the present
invention;
FIG. 11 is an isometric view of an alternate preferred embodiment
of an apparatus of the present invention; and
FIG. 12 is a partially schematic side view of another alternate
preferred embodiment of an apparatus of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The optical recording media prepared with the apparatus of the
present invention or by the method of the present invention
comprises a first member and a second member, the inner surfaces of
which are bonded together with a bonding layer. The first member
comprises a first substrate, a first data storage layer which may
be readable and/or writable, a first inner surface, and a first
outer surface. The second member comprises a second substrate, a
second inner surface, a second outer surface, and optionally a
second data storage layer which may be, if present, readable and/or
writable.
FIG. 1 illustrates (in exploded view) one example of an optical
recording medium 10 which may be made with the apparatus or method
of the present invention. The optical recording medium 10 includes
a first member 12 and a second member 40. First member 12 includes
an inner surface 14 and an outer surface 16 opposite the inner
surface. First member 12 also has an outer diameter (OD) 26 and an
inner diameter (ID) 28. For purposes of explaining the present
invention, it is useful to define an inner surface outer annulus 30
on the first member 12. It is understood that this annulus may
simply be a region on the inner surface 14, and need not be a
discrete identifiable structure or element of the first member 12.
Outer annulus 30 includes a first portion 32 and a second portion
34. In the preferred embodiment, first and second portions 32, 34
are diametrically opposed from one another. Second member 40 of
optical recording medium 10 includes an inner surface 42 and an
outer surface 44 opposite the inner surface. Second member 40 also
includes an outer diameter 48 and an inner diameter 50. As with the
first member 12, it is useful to define an inner surface outer
annulus 52 on the inner surface 42 of the second member. Outer
annulus 52 includes a first portion 54 and a second portion 56
which in the preferred embodiment are diametrically opposed. For
illustrative purposes, the bonding layer 60 between first and
second member 12, 40 is omitted from FIG. 1.
FIG. 2 illustrates a cross section of a portion of the optical
recording medium 10 of FIG. 1, which has been assembled with the
inner surfaces 14 and 42 of the first and second members 12,40
facing one another with a bonding layer 60 therebetween. The
optical recording medium 10 of FIG. 2 is representative of a 4.7 GB
DVD (single side/single layer). The first member 12 comprises a
first substrate 18 having a data storage surface 20 and an outer
surface which in this embodiment also forms the outer surface 16 of
the first member 12. The data storage surface 20 is coated with a
metal layer 22 such as, for example, an aluminum layer which bears
a protective layer 24 thereon. The exposed surface of the
protective layer 24 forms the inner surface 14 of the first member
12. The second member 40 consists in the case of 4.7 GB DVD of a
second substrate 46, having an inner, non-information storing
surface which also forms the inner surface 42 of the second member,
and an outer surface which also forms the outer surface 44 of the
second member. A bonding layer 60 bonds inner surfaces 14 and 42
together. Bonding layer 60 includes a first side 62 facing the
first member 12 and a second side 64 facing the second member
40.
Schematic representations of other, more complicated optical
recording media or DVD constructions are shown, for example, in
ECMA/TC 31/9712; EP 0,725,396; or the Bulletin: 101, December 1996
of Imation Corporation cited above.
The substrates 18, 46 may be of any shape but preferably they are
disks exhibiting a center hole useful for centering the assembled
disks in a recording or playing station. The disk or annulus shaped
substrates preferably have an outer diameter 26, 48 of about 50 to
about 360 mm and an inner diameter 28, 50 of about 5 to about 35
mm, and the thickness of each substrate preferably is between about
0.25 and 1.0 mm and more preferably between about 0.3 and 0.9 mm.
However, it is understood that the apparatus and method of the
present invention are useful with larger and smaller disks. Since
the information is read out and/or written in by means of a light
source such as, for example, a laser having, for example, emission
lines in a wavelength range between 400-700 nm, more preferably
between 600-660 nm, at least one of the substrates and, more
preferably,
both substrates 18, 46 are transparent to visible light, preferably
exhibiting a transparency of at least 90% and more preferably of at
least 95%. The transparency of the substrate can be measured, for
example, according to ASTM D 1746. The substrates may comprise
transparent materials such as glass or polymeric materials with
acrylic resins, polycarbonates, epoxy resins, cyclic olefin
copolymers, and polyolefins being preferred. Especially preferred
are hard plastics such as polymethylmethacrylates or
polycarbonates.
The exposed, outer surfaces 16, 44 of the members 12, 40 may be
formed by the exposed, outer surface of the substrates 18, 46, or
may also bear additional layers such as, for example, a protective
coating layer or a printable or printed film attached to the
exposed surface of the substrate by an adhesive layer.
The inner surfaces 14, 42 of the substrates 18, 46 usually bear one
or more other layers such as, for example, reflecting or
semi-reflecting layers, spacer layers and protective coating
layers. The inner surfaces 14, 42 of the members 12, 40 correspond
to the exposed surface of the outermost layer attached to the inner
surface of the substrate.
Either or both of the substrates 18, 46 may comprise one or more
data storage layers. A data storage layer may be formed by an
information track comprising convex and concave portions (pits)
which may be molded into the inner surface of each substrate. In
DVDs the track pitch typically is about 0.74 .mu.m and the minimum
pit length is about 0.4 pm as can be taken from EP 0,720,159 in
order to provide a sufficiently high information storage density.
Each substrate can comprise one or more further data storage layers
such as, for example, a photopolymer 2P layer as is described, for
example, in EP 0,729,142.
The apparatus and methods of the present invention may be used to
prepare optical recording media having two members the inner
surfaces of which are bonded together with a bonding layer,
preferably a pressure sensitive adhesive layer. The specific
construction of the members can vary widely. Examples of optical
media which can be prepared according to the present invention
comprise but are not restricted to magneto-optical (MO) disks and,
in particular, digital versatile (or sometimes video) disks. DVDs
are described, for example, to some detail in EP 0,729,142, EP
0,725,396 or EP 0,720,159, whereas details on MO disks can be
taken, for example, from U.S. Pat. No. 4,670,316, U.S. Pat. No.
4,684,454, U.S. Pat. No. 4,693,943, U.S. Pat. No. 4,760,012, and
U.S. Pat. No. 4,571,124.
The two members of the optical recording medium are bonded together
with a bonding layer 60. In a preferred embodiment, bonding layer
60 comprises a double sided pressure-sensitive adhesive layer.
Many types of adhesive can be used for bonding layer 60.
Preferably, the adhesive should be free of corrosive ions such as
chloride ions and be capable of forming a flat bonding layer of
uniform thickness so as to not interfere with data output
mechanisms of optical medium. Thus, thermosetting adhesives,
thermoplastic adhesives, and contact adhesive films can be used so
long as they are bondable under temperature and pressure of the
bonding process. Adhesives which remain compliant after application
are preferred because they have less tendency to transmit
vibrations and less tendency to transmit mechanical stresses. The
adhesives are preferred to be thermally, oxidatively, and
hydrolytically stable at storage and use temperatures typically in
the range of -30 to 80.degree. C. The thickness of the bonding
layer/adhesive is usually about 25-75 microns.
Pressure sensitive tapes or sheets, a hot melt adhesive, one-part
or two-part curable compositions (such as thermally curable,
ultraviolet (UV) curable or electron beam curable compositions),
non-tacky contact responsive materials, or one-part anaerobic
adhesives may be used as the bonding layer 60 in the practice of
this invention. Such adhesives can comprise a thermoplastic
elastomer (TPE) or an acrylate, methacrylate, vinyl ether,
isocyanate, silicone, epoxy or urethane group, for example and can
also contain a tackifier, softener, filler, antioxidant, or
crosslinking agent. Preferred adhesives are those comprising
acrylyl, siloxane, saturated hydrocarbon, and urethane polymers.
Acrylate-based pressure sensitive adhesives which are particularly
useful in the present invention include those described in U.S.
Pat. Nos. 4,181,752 and 4,418,120; WO 95/13,331 or in Handbook of
Pressure Sensitive Adhesive Technology; D. Satas ed.; Second
Edition, New York 1989, pp. 396-491.
The pressure sensitive tape can comprise two adhesive layers, with
or without a central substrate. If a central substrate such as
polyester is present, an adhesive layer is present on each side of
a central substrate. An example of a suitable pressure sensitive
tape or sheet is Optically Clear Laminating Pressure Sensitive
Adhesive #8142, available from Minnesota Mining and Manufacturing
Company, St. Paul, Minn. (hereinafter "3M Company").
In general, a hot melt adhesive contains a base polymer and
additives such as a tackifier, plasticizer, and wax. The
ingredients of the adhesive are not particularly limited. The base
polymer may be selected from polyolefinic resins, polyolefinic
copolymers, synthetic rubbers, and mixtures thereof. Examples of
suitable hot melt adhesives are JET MELT Adhesive 3748, a
hydrocarbon resin mixed with rubber, polypropylene, polyethylene,
and aliphatic wax, commercially available from 3M Company, and
those described in U.S. Pat. Nos. 4,503,531; 5,059,462; and
5,188,875; and European Patent Application EP 0 526 244.
The bonding layer can be a non-tacky contact responsive material
which typically is a single film layer of adhesive, which is
usually prepared by coating the adhesive onto a release liner. An
example of non-tacky single layer adhesive is 3M Industrial
Fasteners Non-Tacky Adhesive System SJ 3101 Fastener Strip and SJ
3102 Target Strip, commercially available from 3M Company.
One-part and two-part curable compositions useful in the practice
of the invention include anaerobically curable adhesives such as
those described in U.S. Pat No. 5,244,775; UV curable adhesives
such as described in U.S. Pat. Nos. 5,167,996; 5,244,775;
4,760,012; and 5,214,947, and thermally curable such as epoxy-based
adhesives as described in European Patent Application EP 0 624 870
for example.
The bonding layer can be applied to either or both of the members
of the optical recording medium by any suitable means. Application
methods include the preferred methods described in greater detail
below, along with methods such as spin coating, spray coating, roll
coating, dip coating, printing such as screen printing, lamination,
and the like. The preparation of flat, uniform precision caliper
pressure sensitive adhesive films is described, for example, in WO
95/29,766. The die coating method and the precision coating die
used in this preparation are described in detail in WO 95/29,764
and WO 95/29,765. The bonding layer may be applied to one or both
members of the optical recording medium.
If the bonding layer is curable, the curing may take place before,
during, or after assembly of the members to one another. The curing
can be accomplished by actinic radiation (e.g., UV), heat, or
chemical reaction.
FIG. 3 is an isometric view of a first preferred embodiment of an
apparatus of the present invention useful for carrying out a
preferred embodiment of the method of the present invention.
Apparatus 100 includes a frame 102 having mounting rails 104.
Mounted on the rails 104 are first holder 120 and second holder
220. As illustrated in FIG. 4, first holder 120 and second holder
220 are attached by a flexible linkage 114 such that rotation of
first holder 120 in direction A causes holder 220 to rotate in
direction B. Returning to FIG. 3, extending from first holder 120
is a shaft 128 rotatably mounted by bearings 106 and bearing
supports 108 onto the mounting rail 104. Bearing supports 108 are
slidably mounted on rails 104. Attached to the bearing support 108
is a cylinder 110 which is used to adjust the gap between the first
and second holders 120, 220 or to adjust the force applied between
the two holders.
First holder 120 includes a rotary support 122 having a fixture 140
mounted thereon. Fixture 140 is configured to releasably hold the
first or second member 12, 40 for assembly into optical recording
medium 10. In the illustrated embodiment, the rotary support 122
comprises a circular center plate 124. Attached to the center plate
124 is a center flange 126 for mounting the rotary support 122 onto
the shaft 128. Support 122 also includes an outer shelf 130 for
supporting the fixture 140. In the preferred embodiment, outer
shelf 130 is a circular cylindrical surface. As illustrated in
greater detail in FIG. 5, the first fixture 140 includes a base
142, a base cover 160, an optional resilient pad 168, and a front
surface 170 for releasably holding the first or second member 12,
40. Fixture 140 also includes a locator pin 156 sized and
configured to closely fit the center hole defined by ID 28 or 50 in
the first or second member 12 or 40.
Returning to FIG. 3, shaft 228 extends from second holder 220 and
is rotatably supported by bearing 106 and bearing support 108 onto
mounting rail 104 of the frame 102. Second holder 220 includes a
rotary support 222 and a second fixture 240 for releasably holding
the first or second member 12, 40 for assembly into the optical
recording medium 10. Rotary support 222 includes a center plate
224, which in the preferred embodiment is a circular plate.
Attached to center plate 224 is a center flange 226 for mounting
the rotary support 222 onto shaft 228. Rotary support 222 also
includes an outer shelf 230 attached around the periphery of center
plate 224. In the preferred embodiment, outer shelf 230 defines a
circular cylindrical surface. Mounted to the outer shelf 230 is the
second fixture 240. As seen in greater detail in FIG. 8, second
fixture 240 includes a base 242 attached to the outer shelf 230, a
base cover 260 attached to the base, and an optional resilient pad
268 including a front surface 270. Fixture 240 also includes a
second locator pin 256 for engagement with the center hole defined
by the ID 28, 50 of the first or second member 12, 40.
FIG. 5 is an exploded view of a preferred embodiment of the first
fixture 140. Fixture 140 includes a base 142 having a front surface
143 and rear surface 144. Rear surface 144 is configured to be
attached to the outer shelf 130, such as by bolts. In one preferred
embodiment, a vacuum system is used to releasably attach the first
or second member 12,40 to the fixture 140. In such an embodiment,
base 142 includes a forward vacuum chamber 145 and a rear vacuum
chamber 148. The base 142 includes a forward vacuum port 146 in
communication with the forward vacuum chamber 145 and a rear vacuum
port 150 in communication with the rear vacuum chamber 148. Base
142 also includes a pin mounting hole 152 for receiving a spring
154 and locator pin 156. Locator pin 156 includes tip 158. Attached
to the front surface 143 of the base 142 is a base cover 160. Base
cover includes a front surface 161 and a rear surface 162 which may
be affixed to the front surface 143 of the base such as by bolts.
In the illustrated embodiment, cover 160 provides a seal for the
forward and rear vacuum chambers 145, 148. Cover 160 also includes
a plurality of forward vacuum holes 163 in communication with the
forward vacuum chamber 145 and a plurality of rear vacuum holes 164
in communication with the rear vacuum chamber 148. Cover 160 also
includes a locator pin hole 166 therethrough which is sized to
allow locator pin 156 to extend therethrough while retaining the
locator pin 156 by the large diameter flange at the bottom of the
pin. In the preferred embodiment, front surface 161 of the cover
160 is a convexly curved surface, and in a particularly preferred
embodiment, front surface 161 is an arcuate surface that has a
radius of curvature substantially equal to the radial distance from
surface 161 to the center of rotation of first holder 120.
Also included in the illustrated embodiment of fixture 140 is an
optional resilient pad 168. Resilient pad 168 includes a front
surface 170 and a rear surface 172 which is secured to the front
surface 161 of the base cover such as by an adhesive. Resilient pad
168 also includes in the illustrated embodiment a plurality of
forward vacuum holes 174 in communication with the forward vacuum
chamber through the vacuum holes 163 in the cover 160. Resilient
pad 168 also includes a plurality of rear vacuum holes 176 in
communication with the rear vacuum chamber 148 through the rear
vacuum holes 164 in the base cover 160. Resilient pad 168 also
includes a locator pin hole 175 for allowing locator pin 156 to
extend therethrough.
The assembled fixture 140 is illustrated as being mounted on outer
shelf 130 of the rotary support 122 in FIG. 6. It is seen that
fixture 140 preferably includes a convexly curved outer surface 170
for releasably holding first or second member 12, 40. In
embodiments which include the resilient pad 168, the front surface
of the resilient pad defines the convexly curved surface 170 of the
fixture 140. In a preferred embodiment, this convexly curved
surface is an arcuate surface. In a particularly preferred
embodiment, the radius of curvature of the curved surface 170 is
equal to the radial distance from the surface 170 to the center of
rotation of first holder 120.
In the embodiment illustrated in FIG. 5, fixture 140 includes two
vacuum chambers 145, 148. These vacuum chambers releasably affix
the first or second member 12, 40 to the first fixture 140 via the
holes 163, 174 on the forward side of the fixture and holes 164,
176 on the rearward side of the fixture. Fixture 140 could instead
include a larger number of smaller chambers arrayed across the base
142 with a corresponding number of sets of vacuum holes arrayed
across outer surface 170 of the fixture 140. Furthermore, resilient
pad 168 could instead be a porous pad in communication with a
plurality of vacuum chambers.
In an alternative embodiment of fixture 140 illustrated in FIG. 7,
members 12 and 40 may be releasably affixed by adhesion to the
curved surface 170. This may be through inherent adhesive
characteristics of the resilient pad (e.g., van der Waals forces,
autoadhesion properties, and the like), such as with a silicone
rubber pad. Releasable adhesion of the members to the surface may
also be attained with an adhesive layer applied to the pad. For
example, double sided tape 177 may be used to releasably affix
first or second member 12, 40 to the convexly curved surface 170 of
the fixture 140. In this embodiment, the vacuum chambers and vacuum
holes are not necessary.
FIG. 8 illustrates second fixture 240 mounted on outer shelf 230 of
second rotary support 222. Preferably, second fixture 240 is
constructed in accordance with any of the various embodiments of
first fixture 140 described above. In the embodiment illustrated in
FIG. 8, second fixture 240 includes base 242 mounted on shelf 230.
Base cover 260 is mounted to the front surface of the base 242.
Resilient pad 268 is attached to the front surface of the base
cover 260. Outer surface 270 of the resilient pad forms the
convexly curved surface of the fixture 240 as was described above
with respect to outer surface 170 of first fixture 140. In the
illustrated embodiment, vacuum holes 276 are in communication with
the forward vacuum chamber and rear vacuum holes 274 are in
communication with the rear vacuum chamber of the fixture 240. Pin
256 is shown extending out of the fixture 240.
As illustrated in FIGS. 6 and 7, first holder 140 has associated
therewith an optional tongue segment 178 and first gear segment
180. As shown in FIG. 8, second fixture 240 has associated
therewith a grooved segment 278 and second gear segment 280. The
tongue segment 178 of the first fixture is configured to be
received in the grooved segment 278 associated with the second
fixture. In this way, the lateral relative position of fixtures 140
and 240 can be closely controlled by the engagement of tongue 178
with groove 278. The circumferential position of first fixture 140
relative to second fixture 240 can be closely controlled by the
intermeshing of first gear segment 180 with second gear segment
280. In this way, the first and second members 12, 40 can be
assembled with a high degree of precision of the relative position
between the two members. Such an optional arrangement may not be
necessary for sufficiently rigid and precise fixtures and
holders.
In alternate embodiments of holders 120, 220, the fixtures may
instead be mounted on any suitable rotary support. Examples of such
supports include elongate arms pivotally mounted to a frame, spoked
wheels rather than center plates, or any other similarly
functioning structure. The rotary support may reciprocate back and
forth about its axis of rotation rather than follow a full circular
path about its axis of rotation.
FIGS. 9a, 9b, and 9c are side views of a portion of the preferred
apparatus described above carrying out a preferred embodiment of a
first method according to the present invention. As seen in FIG.
9a, first member 12 of the optical recording medium is mounted on
the convexly curved surface 170 of the first fixture 140. First
member 12 is releasably affixed to the surface 170 (such as by
vacuum or adhesion as described above) with the inner surface 14 of
the first member 12 facing outwardly. Tip 158 of locator pin 156 is
seen extending beyond the inner surface 14 of the first member 12.
Second member 40 of the optical recording medium is releasably
attached to the second convexly curved surface 270 of second
fixture 240. Second member 40 is oriented so as to have inner
surface 42 facing away from the fixture 240. It is thus seen that
the inner surface 14 of the first member is facing the inner
surface 42 of the second member. Tip 258 of second pin 256 is seen
extending beyond the surface of the second member. The first and
second members are mounted on the surfaces 170, 270 of the fixtures
so as to substantially conform to the contour of the surfaces 170,
270. Preferably, at least one of the inner surfaces is convexly
curved. More preferably, both inner surfaces 14, 42 are convexly
curved. Still more preferably, the inner surfaces 14, 42 are curved
to a substantially arcuate configuration. In a particularly
preferred embodiment, the inner surfaces 14, 42 are substantially
arcuate with a radius of curvature substantially equal to the
radial distance from the respective inner surface to the center of
rotation of holders 120, 220.
The method illustrated in FIGS. 9a through 9c is used for applying
a bonding layer 60 to one of the members 12, 40. In the illustrated
embodiment, the method is used to apply bonding layer 60 to the
inner surface 14 of the first member 12. In a preferred embodiment,
bonding layer 60 is a laminating pressure sensitive adhesive which
is provided commercially with a first release liner on its first
surface 62 and a second release liner 68 on its second surface 64.
However, the release liner need not be a separate article provided
with the bonding layer, and instead may be provided on the fixture.
In this regard, the term "release liner" as used herein, including
the claims, refers to any member or surface that is suitable for
temporarily and releasably holding the bonding layer during the
methods described herein. As illustrated, the first release liner
has already been removed from the bonding layer 60. Second release
liner 68 is releasably attached to the inner surface 42 of the
second member 40, such as with an adhesive tape. In this manner,
the exposed surface 62 of the bonding layer 60 is 10 presented for
attachment to the inner surface 14 of the first member 12. First
holder 120 is then rotated in direction A which causes second
holder 220 to rotate in direction B as shown. The first portion 32
of the outer annulus on the inner surface 14 of the first member 12
comes into contact with the first surface 62 of the bonding layer
60. As illustrated in FIG. 9b, rotation of first holder 120 in
direction A and holder 220 in direction B continues. It is seen
that the bonding layer 60 and release liner 68 have been
transferred from the second member 40 to the first member 12 in the
area of the first portion 32 and continuing towards the center of
the first member 12. Spring loaded locating pins 156 and 256 have
contacted one another and depressed one another into their
respective fixtures. As the holders 120, 220 continue to rotate as
illustrated in FIG. 9c, transfer of the bonding layer 60 and
release liner 68 to the inner surface 14 of the first member 12 has
progressed to the second portion 34 of the outer annulus on the
first member. Application of the bonding layer 60 to the first
member is thus substantially complete. Rotation of holders 120 and
220 in directions A and B continues until the first and second
fixtures are clear of one another.
Preferably at least one of the bonding layer 60 and first member 12
are convexly curved when applying the bonding layer. More
preferably, both members 12, 40 are convexly curved during
application of the bonding layer 60 to one of the members. In this
manner, the bonding layer 60 is progressively applied from the
first portion of the inner surface to a diametrically opposed
second portion progressively. This progressive application helps
minimize or eliminate entrapment of bubbles between the bonding
layer 60 and the first member 12. Ideally, contact between the
bonding layer 60 and the first member 12 begins at a point on the
inner surface 14 immediately adjacent the OD 26. However,
satisfactory results are obtained when contact begins at first
portion 32 which is located in the outer annulus 30. It is
understood that first portion 32 may be a small area rather than a
mathematically defined point, and that first portion 32 may be
located a very small distance inward from the OD 26. Alternative to
the illustrated embodiment, the bonding layer 60 may be mounted
directly on surface 270, without second member 40 present.
Furthermore, bonding layer 60 may be initially held by any other
suitable fixture on holder 220, or directly on the outer surface of
shelf 230, or by any other like means. Bonding layer 60 may be
initially applied to either member 12, 40.
The first member 12, with bonding layer 60 thereon, is now ready to
have a second member 40 applied thereto. Preferably, second member
40 is applied by the method described below with respect to FIGS.
10a through 10c. However, it is understood that second member 40
can be applied by any suitable means as desired.
A preferred embodiment of a second method of the present invention
is illustrated with respect to FIGS. 10a through 10c. In this
method, the two members 12, 40 are bonded together to form optical
recording medium 10. In this preferred embodiment of the method,
either or both of the first and second members has a bonding layer
60 already applied thereto. Preferably, bonding layer 60 has been
applied according to the method described above with respect to
FIGS. 9a through 9c. However, it is understood that any suitable
method for applying a bonding layer to either or both of the
members 12, 40 may be used. FIG. 10a illustrates first member 12
releasably mounted onto convexly curved surface 170 of the first
fixture 140, such as by the vacuum arrangement described above with
respect to FIG. 5. First member 12 is releasably attached to
convexly curved surface 170 so as to have its outer surface 16
facing the fixture and its inner surface 14 facing away from the
fixture. Second release liner 68 has been removed from the bonding
layer 60 to thereby expose second surface 64 of the bonding layer
60. Tip 158 of the locating pin 156 extends beyond surface 14 of
the first member. Second member 40 is releasably affixed to the
convexly curved surface 270 of second fixture 240 such as by the
vacuum arrangement described above. Second member 40 is oriented so
as to have outer surface 44 facing the fixture 240 and inner
surface 42 facing away. In this manner the inner surfaces 14, 42 of
the two members are oriented for assembly to one another.
Preferably one, and more preferably both of the surfaces 14, 42 are
convexly curved. Still more preferably, one or both of the surfaces
14, 42 are arcuately curved In the most preferred embodiment, one
or both of the surfaces 14, 42 are arcuately curved so as to have a
radius of curvature substantially equal to the radial distance from
the respective surface and the center of rotation of its respective
holder. Still more preferably, both surfaces 14, 42 have
substantially the same radius of curvature.
As illustrated in FIG. 10a, first holder 120 is rotated in
direction A causing second holder 220 to rotate in direction B so
as to bring first portion 32 of the first member 12 in contact with
the first portion 54 of the second member 40. As used herein,
including the claims, the term "contacting" when used to describe
the assembly of the inner surface 14 and inner surface 42 of the
two members, is used to indicate that the inner surfaces are
contacting one another via the bonding layer 60, that is with the
bonding layer 60 between the inner surfaces. The force of this
contact is determined with cylinder 110, by controlling either the
force exerted by the first holder 120 onto the second holder 220,
or by setting the gap between the two surfaces 170, 270 of the
fixtures. As illustrated in FIG. 10b, rotation of the holders
continues such that the first and second members 12, 40 are bonded
together by bonding layer 60 starting from first portions 32, 52
and progressing towards the centers of the members. Locator pins
156, 256 have contacted one another causing them to retract into
their respective fixtures. The vacuum applied by the forward
chamber 145 in the first fixture 140 and forward chamber 245 in
second fixture 240 has been released in FIG. 10b, allowing the
forward portion of the assembled disk 10 to be released from both
fixtures. Rotation of holder 120 in direction A and 220 in
direction B continues as illustrated in FIG. 10c towards second
portion 34 of the first member and second portion 56 of the second
member. Assembly of the first and second members is substantially
complete at this point, with continued rotation allowing the disk
10 to come free from the two holders as the vacuum applied by the
rearward vacuum chambers is released. Ideally, contact between
members 12 and 40 begins at a point on inner surfaces 14,42
immediately adjacent ODs 26,48, respectively. However, satisfactory
results are obtained when contact begins at first portions 32, 54
which are located in outer annulus 30, 52, respectively. It is
understood that first portions 32, 54 and second portions 34, 56
may be small areas rather than mathematically defined points, and
that these portions may be located a very small distance inward
from the OD of the member.
In embodiments in which an adhesive is used to releasably mount the
first and second members to the curved surfaces 170, 270, the
method illustrated in FIGS. 10a through 10c may differ in that one
of the members may remain on its fixture. As the members are bonded
together, one member will transfer its fixture to the other.
Similarly, the vacuum applied by one fixture may be retained while
the vacuum applied by the other fixture is progressively released
to allow one member to transfer to the other fixture as assembly
progresses from FIGS. 10a through 10c.
By keeping at least one, and preferably both, of the members
curved, assembly progresses from the respective first portions
across the inner surfaces to the respective second portions thereby
minimizing or eliminating trapped air between the bonding layer and
the inner surfaces of the member. By maintaining both members at
substantially the same radius of curvature on the fixtures, the
members have substantially equal and opposite stresses as they are
bonded together at the nip formed between the two fixtures. In this
way, the stress in the assembled optical recording medium 10 is
balanced so as to provide for an optimally flat optical recording
medium 10.
The apparatus and methods described above were described with
respect to a single fixture 140, 240 on each holder 120, 220. It is
understood that for continuous manufacturing processes, it may be
desirable to put a plurality of fixtures 140 and 240 onto each
rotary holder 120, 220. In such an arrangement, linkage 114 as
illustrated may not be suitable for continued rotation of the two
members holders about a full circular path. In such an embodiment,
it would be possible to index rotation of the two holders relative
to one another by use of any other suitable means, such as by a
gear system, a gear and chain system, optical sensors and servos,
and the like.
It may be also desirable to apply the bonding layer 60 continuously
rather than as illustrated in the two methods described above with
respect to FIGS. 9a through 9c and 10a through 10c. FIG. 11 is an
isometric illustration of a preferred apparatus which includes a
third holder 320. This third holder may be provided with die cut
portions of bonding layer 60 for affixation to the first member 12
provided on the first holder 120 in a manner similar to that
described with respect to FIGS. 9a through 9c above, with the
release liner removed continuously as illustrated. First member 12
with bonding 60 thereon is then brought into contact with the
second member 40 which is provided on second holder 220. Bonding
first and second members 12 and 40 together is performed
substantially as described with respect to FIGS. 10a through 10c
above. Furthermore, as long as rotation of each of the respective
holders 120, 220, 320 is indexed, it is not important which of the
holders rotates clockwise or counterclockwise. As illustrated in
FIG. 11, bonding layer 60 may be maintained at a curved, and
preferably arcuate contour, either by being provided on the outer
surface of outer shelf 330 itself, or by any suitable fixture.
In bonding the two members 12, 40 together, it is preferred that
each member be curved substantially to the same degree for the
reasons discussed above. The amount and degree of this curvature
can be determined in accordance with the teachings of the present
application by one skilled in the art and may depend on various
factors such as the size, thickness and material of the members 12,
40, the type and amount of bonding layer 60 used, and by the degree
of flatness that is desired or required. In determining the desired
degree of curvature, it is understood that a larger size holder
120, 220, 320 will result in a greater radius of curvature; that
is, a less curved member. The radius should be selected so as to
provide sufficient curvature to prevent entrapment of air as
described above, while not providing an exceeding amount of
curvature so as to impart an undesirably high amount of stress into
the first and second members during assembly. Similarly, the
material, size, thickness, and hardness of the optional resilient
pad 168, 268, may be determined in accordance with the teachings
herein by one of skill in the art. Suitable materials for the pads
include rubber pads such as silicone rubber, neoprene rubber and
butyl rubber, and foam pads such as polyolefin foam. Each fixture
may have pads of the same or different material, thickness, and
hardness. Suitable results have been achieved with silicone rubber
pads having a Shore A hardness of from 30-70; polyurethane foam
pads having a density of 15 lbs./ft.sup.3 (2360 N/m.sup.3), a
compression force of 13-23 psi (90 to 160 kPa) for 30% deflection,
and a thickness of from 0.0625 to 0.125 in (1.6 to 3.2 mm);
polyurethane foam pads having a density of 25 lbs.ft.sup.3 (3930
N/m.sup.3), a compression force of 51 psi (350 kPa) for 30%
deflection, and a thickness of 0.03 in (0.8 mm); polyurethane foam
pads having a density of 20 lbs./ft.sup.3 (3140 N/m.sup.3), a
compression force of 28 psi (190 kPa) for 30% deflection, and a
thickness of 0.125 in (3.2 mm); and polyethylene foam pads having a
density of 11 lbs./ft.sup.3 (1730 N/m.sup.3), and a thickness of
0.105 in (2.7 mm).
Optionally, a secondary holder may be placed on surface 170. Such a
holder preferably has the same periphery as the resilient pad 168.
The secondary holder is preferably of substantially the same
thickness, strength, and flexibility as the member 12, 40 to be
mounted on the fixture. The secondary holder has a hole therein for
receiving the member 12, 40. In this manner, the exposed surface of
the secondary holder and the inner surface 14, 42 of the member 12,
40 will present a substantially continuous surface.
FIG. 12 is a partially schematic side view of another alternate
preferred embodiment of a holder and fixture. This embodiment
allows use of fixture 440 having convexly curved surface 470 that
has a radius of curvature that is larger than the radius of the
path the fixture travels. Stated another way, the radial distance
from surface 470 to the center of rotation about shaft 128 may be
smaller than the radius of curvature of surface 470. This allows
use of a more compact holder 420 while using a larger radius of
curvature for surface 470, to minimize the amount of bending of
members 12, 40. This may also be used with fixtures in which
surface 470 is not arcuate, but which instead has a radius of
curvatures that varies. One or more fixtures 440 may be mounted on
rotary support 422 of holder 420. In one embodiment, rotary support
422 comprises a center plate 424, having flange 126 and shaft 128
mounted thereto. As with the embodiments discussed above, fixture
440 comprises a base 442, cover 460, optional resilient pad 468,
and locator pin 456. In this embodiment, the fixture 440 is mounted
to the rotary support by a radial mount 490. Radial mount 490
allows the fixture 440 to move radially inward in direction D and
radially outward in direction E as the holder 420 rotates in
direction A. Because the radius of curvature of surface 470 is
different from the distance from surface 470 to the center of
rotation about shaft 128, surface 470 must move radially as the
point of contact progresses from first portion 32 to second portion
34 on the member 12. This can be accomplished by any suitable
radial mount 490. Examples includes a simple slidable mount on the
rotary support 422 and a spring to bias the fixture
440 radially outward Other examples include a mechanically operated
radial mount 490 to positively move the fixture 420 in and out in
response to various input such as the circumferential location of
the fixture, the force imparted on the fixture, or the distance
between opposite fixtures. This arrangement can be used on holders
420 that traverse a full circular path or that reciprocate back and
forth. This arrangement is suitable for applying the bonding layer
to a member and/or for attaching two members together.
In the most preferred embodiment, the bonding layer 60 is applied
by the methods and apparatus described herein, and the members 12,
40 are then bonded together according to the apparatus and methods
described herein. However, the bonding layer 60 may be applied by a
method described herein, and the members 12, 40 subsequently bonded
together by any suitable method. Likewise, bonding layer 60 may be
applied by any suitable alternative method, and the members 12,40
may then be bonded together by the methods and apparatus described
herein. For example, it may be preferable to perform the methods
described herein in a vacuum, in a gas that is highly soluble in
the material of the bonding layer 60, or in a gas that is highly
insoluble in the material of the bonding layer 60. Suitable
alternate methods for applying adhesive, or for assembling disks
together after adhesive has been applied, are taught for example in
U.S. patent application Ser. No. 09/021,255, "Method Of
Manufacturing An Optical Recording Medium" filed on Feb. 10, 1998;
WIPO International Patent Application Publication No. WO 98/08220,
"Process for Bonding Optical Media"; and in Japanese Patent
Application 19523/98, "Bonded Optical Discs As Well As Method And
Apparatus For Producing The Same," inventor Kazuta Saito, et al.,
filed on Jan. 30, 1998, the entire disclosures of all of which are
hereby incorporated by reference.
The operation of the present invention will be further described
with regard to the following detailed examples. These examples are
offered to further illustrate the various specific and preferred
embodiments and techniques. It should be understood, however, that
many variations and modifications may be made while remaining
within the scope of the present invention.
EXAMPLES
Test Methods
Determination of Flatness
The flatness of a bonded disk was determined using a Schenk
Flatness Measurement System, Model No. PLT1, provided by Dr. Schenk
GmbH, Industriemes Stechnik, Munchen, Germany. A bonded sample disk
was placed in a holder and the top and bottom surfaces of the
spinning disk were scanned at points on the inner radius (25 mm),
the middle radius (37 mm), and the outer radius (57 mm) with laser
beams. The maximum and minimum values of the radial deviation and
the tangential deviation were recorded. An industry target for a
disk having acceptable flatness has a radial deviation of+or-0.8
degrees and a tangential deviation of+or-0.3 degrees.
General Preparation of Bonded Disks
Using the apparatus of FIGS. 3 and 4, a first member 12 of a DVD
disk was positioned on the fixture 140 by setting the center hole
of the member over the locating pin. The fixture may additionally
comprise a resilient pad. Pressure sensitive adhesive film sheet
(Optically Clear Laminating Pressure Sensitive Adhesive #8142,
available from 3M Company, St. Paul, Minn., USA) having a thickness
of 58 microns was laid on the second fixture 240. The pressure
sensitive adhesive film had a smooth polyester release liner on the
side that contacted the fixture. The adhesive film was held in
place by 3M 236 Masking Tape laid along the edges of the film.
Vacuum was then applied to hold the first member 12 on the fixture
140. First holder 120 was then rotated approximately 100 degrees.
Second holder 220 followed it by means of a steel band connecting
first and second holders, thus bringing the first member in contact
with the adhesive and laminating it to the first member by means of
the nip created between the fixtures on the holders. The first
member bearing the adhesive was removed from the fixture and the
excess adhesive was trimmed off. The first member bearing the
adhesive was placed back on the fixture so that the adhesive was
facing away from the fixture. A second member of a DVD disk was
positioned on the second fixture 240. Vacuum was applied to hold
both members on the fixtures. First holder 120 was then rotated
approximately 100 degrees bringing the first member bearing the
adhesive in contact with second member by means of the nip created
between the fixtures on the holders. When the first portions of the
outer annuluses of the first and second members entered the nip
area, the vacuum was released from the forward vacuum chambers. The
forward portion of the assembled disk then left the nip tangent to
both fixtures. When the second portions of the outer annuluses of
the first and second members entered the nip area, the vacuum was
released from the rear vacuum chambers. Rotation was continued
until the assembled disk was freed from the holders and it dropped
out of the bottom of the nip.
Examples 1-12
Sample disks were prepared according to the General Preparation of
Bonded Disks described above. In Examples 1-7 and 9-11, the first
and second members were 120 mm in diameter, 0.6 mm in thickness and
made of polycarbonate with an aluminized surface. In Examples 8 and
12, the first member of was 120 mm in diameter, 0.6 mm in thickness
and made of clear polycarbonate and the second member was 120 mm in
diameter, 0.6 mm in thickness, and made of polycarbonate with an
aluminumized surface. A 3.18 mm (0.125 inches) thick silicone
rubber resilient pad was used as part of the fixtures. The
durometer (Shore A Hardness) of the pad was either 60 or 30 as
reported in Table 1 below. The members of Examples 1-10 were held
on the fixtures by vacuum. The members of Examples 11-12 were held
on the fixtures by a double sided pressure sensitive adhesive tape
(3M "DLT" Tape). The force at nip point (nip force) was varied by
changing the air pressure to cylinder 110 and is reported in Table
1 below. The flatness of the bonded disks was determined according
to Determination of Flatness test method outlined above. The radial
deviation and tangential deviation are reported in Table 1.
TABLE 1 ______________________________________ Pad Duro- Radial
Tangential meter Measurement Deviation Deviation (Shore Nip Force
Position on (degrees) (degrees) Ex. A) Kg. (lbs) Disk Radius Min.
Max. Min. Max. ______________________________________ 1 60 71.4
(157) Inner, top -0.38 -0.05 -0.20 +0.25 Inner, bottom +0.05 +0.42
-0.26 +0.21 Middle, top -0.39 -0.01 -0.22 +0.27 Middle, bottom
+0.04 +0.44 -0.29 +0.21 Outer, top -0.43 +0.03 -0.28 +0.24 Outer,
bottom -0.03 +0.48 -0.24 +0.27 2 60 71.4 (157) Inner, top -0.24
+0.00 -0.16 +0.13 Inner, bottom +0.04 +0.27 -0.15 +0.18 Middle, top
-0.35 -0.03 -0.15 +0.15 Middle, bottom +0.06 +0.39 -0.18 +0.16
Outer, top -0.44 +0.32 -0.13 +0.17 Outer, bottom +0.03 +0.44 -0.19
+0.15 3 60 57.3 (126) Inner, top -0.47 +0.05 -0.18 +0.16 Inner,
bottom -0.05 +0.49 -0.17 +0.20 Middle, top -0.47 +0.17 -0.17 +0.17
Middle, bottom -0.17 +0.51 -0.19 +0.17 Outer, top -0.52 +0.31 -0.27
+0.26 Outer, bottom -0.31 +0.57 -0.27 +0.25 4 60 57.3 (126) Inner,
top -0.24 +0.02 -0.08 +0.06 Inner, bottom +0.02 +0.25 -0.07 +0.09
Middle, top -0.30 +0.12 -0.06 +0.09 Middle, bottom -0.07 +0.32
-0.09 +0.07 Outer, top -0.44 +0.30 -0.23 +0.25 Outer, bottom -0.14
+0.63 -0.19 +0.23 5 30 86.8 (191) Inner, top -0.25 +0.09 -0.05
+0.10 Inner, bottom -0.12 +0.29 -0.12 +0.07 Middle, top -0.39 +0.20
-0.14 +0.17 Middle, bottom
-0.17 +0.45 -0.21 +0.12 Outer, top -0.51 +0.53 -0.31 +0.27 Outer,
bottom -0.33 +0.56 -0.29 +0.31 6 30 86.8 (191) Inner, top -0.41
+0.00 -0.14 +0.16 Inner, bottom -0.03 +0.43 -0.18 +0.14 Middle, top
-0.52 +0.07 -0.10 +0.21 Middle, bottom -0.06 +056 -0.23 +0.12
Outer, top -0.65 +0.19 -0.18 +0.26 Outer, bottom -0.24 +0.65 -0.29
+0.17 7 30 57.3 (126) Inner, top -0.43 +0.01 -0.17 +0.15 Inner,
bottom +0.02 +0.42 -0.14 +0.17 Middle, top -0.40 -0.06 -0.18 +0.17
Middle, bottom +0.06 +0.41 -0.17 +0.18 Outer, top -0.35 -0.07 -0.21
+0.19 Outer, bottom +0.07 +0.40 -0.17 +0.22 8 30 57.3 (126) Inner,
top -0.57 +0.37 -0.29 +0.25 Inner, bottom -0.38 +0.55 -0.23 +0.28
Middle, top -0.30 +0.43 -0.34 +0.30 Middle, bottom -0.42 +0.32
-0.27 +0.34 Outer, top -0.04 +0.66 -0.45 +0.36 Outer, bottom -0.66
+0.01 -0.33 +0.45 9 30 142.7 Inner, top -0.35 +0.19 -0.22 +0.26
(314) Inner, bottom -0.19 +0.34 -0.25 +0.19 Middle, top -0.35 +0.19
-0.33 +0.33 Middle, bottom -0.19 +0.36 -0.32 +0.29 Outer, top -0.39
+0.20 -0.44 +0.40 Outer, bottom -0.20 +0.36 -0.40 +0.40 10 30 28.6
(63) Inner, top -0.53 +0.24 -0.30 +0.32 Inner, bottom -0.42 +0.57
-0.32 +0.32 Middle, top -0.55 +0.24 -0.40 +0.42 Middle, bottom
-0.25 +0.60 -0.42 +0.43 Outer, top -0.58 +0.30 -0.44 +0.48 Outer,
bottom -0.16 +0.63 -0.49 +0.47 11 30 28.6 (63) Inner, top -0.25
+0.14 -0.15 +0.18 Inner, bottom -0.15 +0.27 -0.17 +0.17 Middle, top
-0.24 +0.11 -0.22 +0.20 Middle, bottom -0.12 +0.25 -0.17 +0.24
Outer, top -0.30 +0.18 -0.27 +0.25 Outer, bottom -0.12 +0.36 -0.22
+0.28 12 60 71.4 (157) Inner, top -0.43 -0.01 -0.33 +0.21 Inner,
bottom -0.02 +0.42 -0.19 +0.34 Middle, top -0.45 +0.05 -0.42 +0.16
Middle, bottom -0.03 +0.46 -0.17 +0.43 Outer, top -0.32 +0.45 -0.50
+0.30 Outer, bottom -0.47 +0.29 -0.30 +0.49
______________________________________
Examples 13-15
Sample disks were prepared as described in Examples 1-12 described
above except that 3.94 mm (0.155 inches) thick polyethylene foam,
prepared by combining several thickness of foam, was used in place
of the silicone rubber as the resilient pad For Example 13, the
first member and second members were the same as those used for
Examples 1-7 and 9-11. For Examples 14 and 15, the first and second
members were the same as those used for Examples 8 and 12. The
members of Examples 13 and 14 were held on the fixtures by vacuum.
The members of Examples 15 were held on the fixtures by a double
sided pressure sensitive adhesive tape (3M "DLT" Tape). The force
at nip point (nip force) was 57.3 kg.(126 lbs). The flatness of the
bonded disks was determined according to Determination of Flatness
test method outlined above. The radial deviation and tangential
deviation are reported in Table 2.
TABLE 2 ______________________________________ Radial Tangential
Measurement Deviation Deviation Position on (degrees) (degrees) Ex.
Disk Radius Min. Max. Min. Max.
______________________________________
13 Inner, top -0.30 -0.02 -0.08 +0.10 Inner, bottom +0.02 +0.34
-0.11 +0.07 Middle, top -0.30 -0.02 -0.10 +0.11 Middle, bottom
+0.02 +0.35 -0.13 +0.12 Outer, top -0.26 +0.04 -0.15 +0.19 Outer,
bottom -0.03 +0.41 -0.19 +0.16 14 Inner, top -0.53 +0.09 -0.24
+0.16 Inner, bottom -0.10 +0.48 -0.15 +0.22 Middle, top -0.22 +0.18
-0.26 +0.19 Middle, bottom +0.17 +0.24 -0.17 +0.24 Outer, top +0.03
+0.55 -0.29 +0.25 Outer, bottom -0.59 -0.04 -0.23 +0.28 15 Inner,
top -1.29 +0.40 -0.39 +0.32 Inner, bottom -0.39 +1.35 -0.31 +0.36
Middle, top -1.24 +0.82 -0.54 +0.44 Middle, bottom -0.77 +1.24
-0.43 +0.50 Outer, top -1.02 +1.31 -0.68 +0.59 Outer, bottom -1.32
+0.96 -0.58 +0.62 ______________________________________
Examples 16-20
These Examples demonstrate that during the step of applying the
bonding layer of the process of the invention additional stress in
not induced into a disk member.
The flatness of a sample disk member 120 mm in diameter, 0.6 mm in
thickness and made of polycarbonate with an aluminized surface
(same as used for Examples 1-7 and 9-11) was determined according
to Determination of Flatness test method outlined above. Then,
using the apparatus of FIGS. 3 and 4, the sample member was
positioned on the 3.18 mm (0.125 inches) thick Shore A hardness 30
silicone rubber resilient pad of fixture 140 by setting the center
hole of the member over the locating pin. Pressure sensitive
adhesive film sheet (Optically Clear Laminating Pressure Sensitive
Adhesive #8142, available from 3M Company, St Paul, Minn., USA)
having a thickness of 58 microns was laid on the 3.18 mm (0.125
inches) thick Shore A hardness 30 silicone rubber resilient pad of
second fixture 240. The pressure sensitive adhesive film had a
smooth polyester release liner on the side that contacted the
fixture. The adhesive film was held in place by 3M 236 Masking Tape
laid along the edges of the film. For examples 16-19, vacuum was
used to hold the first member 12 on the fixture 140. For example
20, the autoadhesion of the silicone resilient pad was used to hold
the first member on the fixture. First holder 120 was then rotated
approximately 100 degrees. Second holder 220 followed it by means
of a steel band connecting first and second holders, thus bring the
first member in contact with the adhesive and laminating it to the
first member by means of the nip created between the fixtures on
the holders. Nip force was 57.3 kg. (126 lbs). The first member
bearing the adhesive film was removed from fixture and the excess
adhesive film was trimmed off. The liner was removed from the
adhesive film and the flatness of the member with adhesive attached
was determined according to Determination of Flatness test method
outlined above. The radial deviation and tangential deviation of
the member with and without the adhesive are reported in Table
3.
TABLE 3
__________________________________________________________________________
Tangential Tangential Radial Deviation Deviation Radial Deviation
Deviation Measurement Without Adhesive Without Adhesive With
Adhesive With Adhes- Position on (degrees) (degrees) (degrees) ive
(degrees) Ex. Disk Radius Min. Max. Min. Max. Min. Max. Min. Max.
__________________________________________________________________________
16 Inner, top -0.31 +0.33 -0.28 +0.35 -0.11 +0.39 -0.23 +0.27
Inner, bottom -0.32 +0.30 -0.35 +0.26 -0.41 +0.11 -0.27 +0.21
Middle, top +0.35 +0.69 -0.31 +0.40 +0.51 +0.79 -0.23 +0.32 Middle,
bottom -0.66 -0.31 -0.38 +0.29 -0.78 -0.49 -0.31 +0.21 Outer, top
+0.70 +1.19 -0.20 +0.32 +0.72 +1.14 -0.15 +0.26 Outer, bottom -1.19
-0.69 -0.31 +0.10 -1.32 -0.75 -0.24 +0.16 17 Inner, top +0.07 +0.58
-0.26 +0.21 +0.00 +0.45 -0.15 +0.15 Inner, bottom -0.57 -0.09 -0.21
+0.24 -0.46 -0.04 -0.16 +0.15 Middle, top +0.35 +0.91 -0.27 +0.32
+0.12 +0.81 -0.17 +0.28 Middle, bottom -0.87 -0.35 -0.30 +0.26
-0.80 -0.09 -0.25 +0.17 Outer, top +0.58 +1.23 -0.30 +0.46 +0.29
+1.06 -0.34 +0.38 Outer, bottom -1.25 -0.56 -0.44 +0.29 -1.15 -0.29
-0.37 +0.36 18 Inner, top +0.19 +0.59 -0.25 +0.28 +0.07 +0.50 -0.14
+0.21 Inner, bottom -0.58 -0.19 -0.28 +0.24 -0.51 -0.06 -0.23 +0.15
Middle, top +0.46 +0.78 -0.27 +0.36 +0.39 +0.71 -0.16 +0.29 Middle,
bottom -0.75 -0.43 -0.36 +0.26 -0.68 -0.36
-0.30 +0.15 Outer, top +0.75 +1.06 -0.25 +0.39 +0.70 +0.95 -0.22
+0.30 Outer, bottom -1.08 -0.73 -0.40 +0.24 -1.07 -0.74 -0.32 +0.23
19 Inner, top +0.08 +0.66 -0.21 +0.17 +0.04 +0.52 -0.16 +0.21
Inner, bottom -0.65 -0.06 -0.17 +0.23 -0.56 -0.02 -0.21 +0.17
Middle, top +0.13 +0.86 -0.22 +0.18 +0.25 +0.83 -0.18 +0.22 Middle,
bottom -0.82 -0.12 -0.19 +0.24 -0.83 -0.23 -0.21 +0.20 Outer, top
+0.31 +1.13 -0.24 +0.30 +0.40 +1.07 -0.27 +0.29 Outer, bottom -1.16
-0.31 -0.32 +0.24 -1.21 -0.42 -0.30 +0.28 20 Inner, top -0.07 +0.29
-0.20 +0.29 +0.02 +0.49 -0.18 +0.31 Inner, bottom -0.29 +0.08 -0.28
+0.19 -0.50 -0.03 -0.32 +0.16 Middle, top +0.07 +0.61 -0.25 +0.28
+0.33 +0.78 -0.15 +0.30 Middle, bottom -0.59 -0.05 -0.27 +0.24
-0.76 -0.30 -0.29 +0.14 Outer, top +0.36 +1.06 -0.30 +0.28 +0.52
+1.02 -0.21 +0.29 Outer, bottom -1.09 -0.33 -0.27 +0.29 -1.12 -0.54
-0.28 +0.21
__________________________________________________________________________
Examples 21-24
These examples illustrate a method of assembling a disk using the
process of this invention to apply a bonding layer to a first
member and a second, different process to apply the second member
to the first member.
A single first member having an adhesive film (i.e., with release
liner on the adhesive) on one side was prepared using the materials
and the method described in Examples 16-19 except that the nip
force was not recorded but believed to be in the range of
57.3-136.4 kg. (126-300 lbs). For Examples 21 and 22, the disk
member was the same as that used for Examples 1-7, and 9-11. For
Examples 23 and 24, the disk member was the same as that used for
Examples 8 and 12. The release liner was removed to expose the
adhesive and a second disk member was bonded to the first disk
member via the adhesive using the apparatus described in and shown
in FIG. 4 of Japanese Patent Application 19523/98, "Bonded Optical
Discs As Well As Method And Apparatus For Producing the Same",
inventor Kazuta Saito et al., filed on Jan. 30, 1998. Specifically,
the members were placed in the bonding apparatus in a predetermined
position, and bonded to each other under reduced pressure of 1.0
Torr. The flatness of the bonded disks was determined according to
Determination of Flatness test method outlined above. The radial
deviation and tangential deviation are reported in Table 4.
TABLE 4 ______________________________________ Radial Tangential
Measurement Deviation Deviation Position on (degrees) (degrees) Ex.
Disk Radius Min. Max. Min. Max.
______________________________________ 21 Inner, top -0.34 -0.01
-0.15 +0.22 Inner, bottom +0.03 +0.34 -0.22 +0.14 Middle, top -0.30
-0.01 -0.15 +0.24 Middle, bottom +0.02 +0.29 -0.24 +0.13 Outer, top
-0.33 +0.02 -0.19 +0.26 Outer, bottom -0.10 +0.25 -0.25 +0.18 22
Inner, top -0.29 +0.00 -0.06 +0.07 Inner, bottom +0.01 +0.29 -0.07
+0.08 Middle, top -0.33 +0.01 -0.07 +0.09 Middle, bottom +0.00
+0.32 -0.09 +0.07 Outer, top -0.43 +0.01 -0.13 +0.13 Outer, bottom
-0.10 +0.35 -0.15 +0.13 23 Inner, top -0.55 -0.09 -0.22 +0.19
Inner, bottom +0.11 +0.53 -0.18 +0.20 Middle, top -0.43 -0.04 -0.20
+0.15 Middle, bottom +0.06 +0.40 -0.15 +0.18 Outer, top -0.31 +0.12
-0.13 +0.16 Outer, bottom -0.17 +0.23 -0.15 +0.11 24 Inner, top
-0.59 -0.01 -0.15 +0.25 Inner, bottom +0.02 +0.62 -0.25 +0.14
Middle, top -0.50 -0.06 -0.20 +0.27 Middle, bottom +0.05 +0.50
-0.28 +0.19 Outer, top -0.34 +0.02 -0.22 +0.26 Outer, bottom -0.10
+0.24 -0.25 +0.20 ______________________________________
The tests and test results described above are intended solely to
be illustrative, rather than predictive, and variations in the
testing procedure can be expected to yield different results.
All patents and patent applications cited herein are hereby
incorporated by reference.
The present invention has now been described with reference to
several embodiments thereof. The foregoing detailed description and
examples have been given for clarity of understanding only. No
unnecessary limitations are to be understood therefrom. It will be
apparent to those skilled in the art that many changes can be made
in the embodiments described without departing from the scope of
the invention. Thus, the scope of the present invention should not
be limited to the exact details and structures described herein,
but rather by the structures described by the language of the
claims, and the equivalents of those structures.
* * * * *
References